Large-Field CO (J = 1→0) Observations of the Starburst Galaxy M 82

• Published in: Publications of the Astronomical Society of Japan Vol. 65; no. 3
• Main Authors: Salak, Dragan, Nakai, Naomasa, Miyamoto, Yusuke, Yamauchi, Aya, Tsuru, Takeshi G.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford University Press 25.06.2013
• Subjects: galaxies: starburst; galaxies: individual (M 82); galaxies: interactions; galaxies: ISM
• ISSN: 0004-6264; 2053-051X
• DOI: 10.1093/pasj/65.3.66

We present large-field (15.7 $ \times$ 16.9 arcmin $ ^2$ ) CO ( $ J$ $ =$ 1 $ \rightarrow$ 0) observations of the starburst galaxy M 82, at an angular resolution of 22 $ ''$ with the NRO 45-m telescope. The CO emission was detected in the galactic disk, outflow (driven by the galactic wind) up to $ \sim$ 2 kpc above the galactic plane in the halo, and in tidal streams. The kinematics of the outflow (including CO line splitting) suggests that it has the shape of a cylinder that is diverging outwards. The mass and kinetic energy of the molecular gas outflow are estimated to be (0.26–1.0) $ \times$ 10 $ ^{9}\ M_{\odot}$ and (1–4) $ \times$ 10 $ ^{56}$ erg. A clump of CO gas was discovered 3.5 kpc above the galactic plane; it coincides with a dark lane previously found in X-ray observations, and a peak in H I emission. A comparison with H I, hot molecular hydrogen and dust suggests that the molecular gas shows signatures of warm and cool components in the outflow and tidal streams, respectively.